The embodiment described herein relates generally to the field of fault detection in permanent magnet synchronous machines (PMSM) and the subsequent management of the faults after detection. The field reconstruction method (FRM) is utilized in a magnetic flux observer system to (a) detect faults and (b) optimize the torque in a PMSM in real time.
In order to detect faults in an electromechanical energy converter, knowledge of the distribution and behavior of the magnetic field is necessary. Present tools for magnetic field analysis mainly use the finite element analysis (FEA) to find the distribution of the magnetic field in the electromechanical energy conversion unit. Although accurate, the main problem with FEA based methods is the amount of time which is necessary to carry out the task. Therefore FEA methods are inappropriate for real time control schemes. Also, FEA methods increase the computational expense of the whole system. In addition, there are issues in flux estimation using conventional methods as they use voltage integration which leads in significant numerical errors in low speed applications. One of the main areas in which the magnetic field analysis is applicable is the observation of the magnetic flux passing through the stator teeth in an electrical machine. Normally, a set of search coils are mounted on the machine to sense induced voltages. Then the data from the sensors would be fed into the DSP to be converted into corresponding flux linkage values. The magnetic flux observer method here gives the same results with acceptable accuracy while using only the phase currents. For the purpose of calibration, the estimated flux values may be compared to actual values measured using the search coils. Once the magnetic flux observer is calibrated it may be used to detect faults such as inter-turn short-circuits, rotor eccentricity, and PM demagnetization.